Does weight loss reduce the severity and incidence of psoriasis or psoriatic arthritis? A Critically Appraised Topic.

Clinical Question: Does weight loss reduce the severity and incidence of psoriasis or psoriatic arthritis (PsA) in obese individuals?
Background: Obesity presents a rising public health challenge and is more prevalent among individuals with psoriasis or PsA than in the general population. Longitudinal population-based studies suggest a causal role for obesity in psoriasis and PsA onset and that obesity drives greater disease severity.
Methods: We systematically reviewed evidence within the MEDLINE, Embase and CENTRAL databases and clinical trials registries examining lifestyle, pharmacological and surgical weight loss interventions in the treatment and prevention of psoriasis and PsA in obese individuals. Meta-analysis was conducted using random-effects models, followed by sensitivity analyses.
Results: Of 176 full-text articles reviewed, 14 met the inclusion criteria. Meta-analysis of six randomized control trials (RCTs) confirmed that weight loss following lifestyle interventions (diet or physical activity) improves psoriasis compared with control [mean change in Psoriasis Area and Severity Index -2·59, 95% confidence interval (CI) -4·09 to -1·09; P < 0·001]. One RCT demonstrated a greater likelihood of achieving minimal PsA activity following diet-induced weight loss (odds ratio 4·20, 95% CI 1·82-9·66; P < 0·001). Three studies of pharmacological treatments reported conflicting results, and no RCTs of bariatric surgery were identified. Two cohort studies suggested that bariatric surgery, particularly gastric bypass, reduces the risk of developing psoriasis (hazard ratio 0·52, 95% CI 0·33-0·81; P < 0·01).
Conclusions: These limited data indicate that weight loss can improve pre-existing psoriasis and PsA, and prevent the onset of psoriasis in obese individuals. Together with the National Institute for Health and Care Excellence obesity guidance, this informed a local obesity screening and management pathway, providing multidisciplinary weight loss interventions alongside conventional skin-focused care for patients with psoriasis.
(© 2019 British Association of Dermatologists.)